Cheater advice

So I found once again that my boyfriend of 3 years has cheated on me. We bought a house last year and it's still not finished and I was stupid and let him rack up my credit cards to try and get some things done for the house since we maxed out the loan due to a series of unfortunate events with the house. So I don't really have the choice of up and leaving due to debt. Anyway after finding out of him cheating most recently we got into a huge fight but Im too much of a softie and we decided to try and work things out because we don't want to just lose everything we have worked for. The problem is I just can't get over the hurtful things he would tell other people about me and the cheating in general the messages he would send to other women but claimed he didn't have time for me. Im trying to ignore it and work on our relationship but it just keeps putting me im severe depression, and we keep fighting because I cant stop thinking about it and getting angry. I've been cheated on so much in my life, that I start to wonder wtf is wrong with me. I guess I just need advice on how to deal with it cuz its eating away at me and I dont know what to do, I dont want to throw away our relationship but I dont know if I can ever trust anyone again.